Cold start method and apparatus for carrying out same

ABSTRACT

Reference is hereinafter had to a cold start system for a sparkignition, internal combustion engine in which a greater fraction of lower molecular weight constituents can be quickly and easily separated from a full-range gasoline i.e., a hydrocarbon mixture of full-range components, as cold start is initiated. The separation system includes a miniature vertical countercurrent stripping column positioned within the engine compartment. The stripping column has separate inlet and outlet conduits in selective fluid contact with a stream of full-boiling gasoline passing to the stripping column from the gas tank by way of a fuel pump. Entry of the gasoline into the column is regulated by a conduit and valve network under control of a controller circuit initiated by the tripping of an ignition switch.

United States Patent 119.

Senger July 1, 1975 COLD START METHOD AND APPARATUS 3,783,841 1/1974 Hirschler et a1. 123/127 FOR CARRYING OUT SAME 3,783,849 H1974 Bramfitt 123/123 [75] Inventor: John F. Senger, Berkeley, Calif. Primary Examiner charles J Myhre [73] Assignee: Chevron Research Company, San Assistant ExaminerW. Rutledge, Jr.

Francisco, Calif. Attorney, Agent, or FirmHarold D. Messner; Ralph 221 Filed: Nov. 12, 1973 [21] Appl. No.: 415,070 57 ABSTRACT Relaled Applicamm Data Reference is hereinafter had to a cold start system for [63] Continuation of Ser. No. 295,041, Oct. 4, 1973, a spark-ignition, internal combustion engine in which abandoned. a greater fraction of lower molecular weight constituents can be quickly and easily separated from a full- [52] US. Cl 123/127; 123/135; 123/180 R range gasoline i.e., a hydrocarbon mixture of full- [51] Int. Cl. F02m l/l6 range components, as cold start is initiated. The sepa- [58] Field of Search 123/3, 133, 135, 127, 179 G, ration system includes a miniature vertical countercur- 123/180 R, 180 A. 180T rent stripping column positioned within the engine compartment. The stripping column has separate inlet [56] References Cited and outlet conduits in selective fluid contact with 21 UNITED STATES PATENTS stream of full-boiling gasoline passing to the stripping 565,828 8/1896 Best 123/135 X Column from the gas tank by way of a fuel Pump- ],490192 4/1924 Anderson [23/121 Entry of the gasoline into the column is regulated by 21 1559214 10 925 woo|son I I I 123 3 conduit and valve network under control of a control- 1,6l9,612 3/1927 Grudzinski.. 123/180 I ler circuit initiated by the tripping of an ignition 1,744,953 1/1930 Dienner 123/3 switch. 2,768,496 10/1956 Stamm et a1.... 123/127 X 3,688,755 0/1972 Grayson et a1 123 3 1 Claim 3 Drawing Figures COLD START METHOD AND APPARATUS FOR CARRYING OUT SAME This is a continuation of Ser. No. 295,041 filed Oct. 4, 1973. now abandoned.

RELATED APPLICATIONS Title lnventorts) Ser. No.

use a more volatile fuel under a multiplicity of operating conditions of a spark-ignition internal combustion engine (particularly during cold start), a greater fraction of lower molecular weight constituents can be separated from a full-range gasoline i.e., a hydrocarbon mixture of full-range components, as cold start is initiated. The separation system includes a miniature vertical countercurrent stripping column positioned within the engine compartment. The stripping column has separate inlet and outlet conduits in selective fluid contact with a stream of full-boiling gasoline passing to the stripping column from the gas tank by way of a fuel Two-Stage Cold Start and Evaporative Control System and Apparatus for Carrying Out Same Fuel injection Cold Start and Evaporative Control Method and Apparatus for Carrying Out Same Sigmund M. Csicsery Pat. No.

Sigjmund M. Csicsery an Pat. No. Bernard F. Muluskey Sigmund M. Csicse ry Pat. No.

Two-Stage Fuel ln' ction Cold Start Met and Apparatus for Carrying Out Same Sigmund M. Csicsery and Bernard F. Mulaskey Pat. No.

295.028 now 295.029 now 295,040 now 295.030 now The present invention relates to cold starting of a spark-ignition internal combustion engine and has for an object the provision of a simple, effective and novel cold start system for use in such engine for selectively separating from a full-range fuel flowing to the engine, an increased fraction of lower molecular weight constituents so as to allow quick starting of the engine without producing excessive amounts of unoxidized hydrocarbons at the exhaust. The stripped higher molecular weight fractions during cold start are recycled to the gas tank for later use in the engine fuel system, say after the engine has been warmed and the full range fuel is being utilized.

During cold start of spark-ignition internal combustion engines, the fuel-air ratio is generated by the airfuel intake system, say a conventional carburetion system. At cold start, the air-fuel ratio can be varied (enriched) to assure adequate amounts of low molecular weight constituents of the fuel at the intake manifold. By operation of a plurality of interrelated well-known parts, the lower molecular weight constituents become more easily vaporized to form combustible vaporfuel/air ratios to allow starting of the engine even at low operating temperatures. However, since remaining higher molecular weight constituents are not oxidized even if the start is rapid, such remaining constituents contribute to the formation of unburned hydrocarbons at the exhaust.

Although a more volatile fuel having a lower boiling point, would permit faster starts and warmup as well as reduce exhaust pollutants including unburned hydrocarbons and carbon monoxide emissions at the exhaust, experience shows that the full range engine performance using the more volatile fuel would be adversely affected. in this regard, fuel consumption would be greatly increased over all ranges of driveability.

In accordance with the present invention, rather than pump. Entry of the gasoline into the column is regulated by a conduit and valve network under control of a controller circuit initiated by the tripping of an ignition switch. The column includes a series of interconnected stacked trays, each provided with, say, a plurality of side-by-side baffles for bringing downwardly traveling full-boiling gasoline into intimate contact with upwardly traversing air. In that way, successive vaporizations of the downwardly cascading fuel occurs at each tray. As a result, an enriched overhead vapor product containing a greater fraction of lower molecular weight components is provided at the outlet of the column. From the stripping column, the overhead product passes into a condenser (say positioned at the firewell of the engine adjacent the stripping column) and, after liquefaction, thence into a fuel well of the carburetor. The fuel is then mixed with passing air to form a combustible air-fuel ratio. The air-fuel mixture is then passed through an inlet manifold into the combustion chambers of the engine and consumed. Since the overhead product comprises an abundance of lower molecular weight components, the result is easier starting of the engine under a variety of conditions without formation of undue pollutants at the exhaust. The bottom product of the column containing stripped higher molecular weight fuel components is simultaneously recycled to the gasoline tank. After being mixed with the full-range fuel within the gas tank, the bottom product is available for later use, say when the engine has warmed.

Construction of the countercurrent stripping column within the engine compartment can vary. Preferably, the arrangement resembles that provided in a stripping tower wherein feed gasoline--during cold start--passes downwardly through the column as countercurrent air is conveyed upwardly relative to the cascading fuel. Selective separation of the higher molecular weight constituents vis-a-vis lower molecular weight componentsoccurs so that during start-up, the greater concentra tion of the latter constituents makes up the overhead product and passes into the fuel well of the carburetor to be mixed with air in a selected air-fuel ratio for later combustion within the combustion chambers of the engine. Since the starting cycle of an internal combustion engine is quite short, say from less than 1 to 15 seconds (exclusive of starting problems), the required quantity of overhead product to initiate starting can be surprisingly low (say from 400-500 milliliters per cold start).

Further objects, features and attributes of the present invention will become apparent from a detailed description of a selected embodiment, the description to be taken in conjunction with the following drawings in which:

FIG. 1 is a schematic view of a portion of an engine and fuel system illustrating a typical carburetor and air cleaner assembly interconnected between a cold start system separation (stripping) column housed within the engine compartment in fluid contact with a full boiling gasoline passing from a gasoline tank via a fuel pump and a valve and conduit network under control of a controller circuit;

FIG. 2 is a fragmentary view of a metering pin useful in the valve and conduit network of FIG. 1;

FIG, 3 is a fragmentary view of the valve and conduit network of FIG. 1 illustrating the position of a cold start valve after cold start has been achieved and the engine is at running temperature.

Referring now to FIG. 1, there is illustrated in the engine fuel system connected to an engine intake manifold ll of a spark-ignition internal combustion engine. Fuel system 10 includes an air intake system 12, a carburetor 13, a fuel intake system 14 which includes cold start sytem 15 of the present invention.

To form a combustible air-fuel mixture, air enters by way of air intake system 12, say by an air inlet line (not shown) and is filtered at an air filter 16 interior of an air filter housing 16a, before entry into carburetor l3. Carburetor 13 includes choke and throttle valves 17 and 18, respectively, a fuel well 19 and a discharge nozzle 20. Fuel well 19 contains a metered amount of gasoline to be mixed with air passing discharge nozzle 20. The resulting air-fuel mixture passes through intake manifold ll into the engine combustion chambers (not shown) where combustion occurs.

Supplying fuel well 19 with a metered quantity of gasoline is by way of fuel intake system 14 including a gas tank 23 containing a reservoir of full-range fuel (i.e., a full-boiling mixture of hydrocarbons), a fuel pump 24 and cold start system 15 of the present invention. Cold start system 15 includes a valve and conduit network 25 having a cold start rotary valve 250 in fluid contact with discharge sides of fuel pump 24 and condenser 27. Valve and conduit network 25 is under operative control of a controller circuit 26. Valve and conduit network 25 also includes a valve metering unit 25b connected to the discharge side of rotary valve 250 and a spring loaded one-way valve 25c located at the dis charge side of condenser 27. The valve metering unit 251) meters selected amounts of gasoline via conduit 28 to stripping column 29. Cold start rotary valve 250 is controlled by relay means 260 of controller circuit 26, the rotary valve 25a being mechanically controlled through mechanical transducer 25d and electrically controlled through bimetal temperature switch 26h, ig-

nition switch 26c and battery 26d. Transducer 25d converts rectilinear travel of the relay means 26a to rotational movement for activating rotary cold start valve 25a as explained below. In shunt with relay means 26a is seen to be motor 26e, electrically controlled through bimetal temperature switch 26g. When activated, motor 26e drives air blower 26h to pass air via conduit 31 into stripping column 29 and thence upwardly through stripping column 29 countercurrent to the downward flow of the full-boiling gasoline.

Construction of the stripping column 29 can vary. Preferably, the column 29 includes a series of horizontally extending, stacked trays, each tray including a multiplicity of side-by-side baffles to allow the cascading feed gasoline entering by way of conduit 28 to flow downwardly and be place in intimate contact with the upwardly traveling air. As the downwardly flowing feed gasoline is spread horizontally up on each tray in rather thin sections, the area of exposure to evaporation is enhanced to allow increased evaporation (stripping) of lower molecular weight constituents from the fullrange fuel. Temperature differences existing between the upwardly moving air saturated with hydrocarbons can cause each tray (in addition to acting as a vaporizer) to also act as a partial condenser; i.e., ascending vapor comes into intimate contact with cooler downwardly traveling liquid wherein the less volatile components can be partially condensed as more volatile components from the liquid are vaporized. From column 29, the overhead comprising an increased concentration of lower molecular weight constituent product is conveyed via conduit 30 through condenser 27 and thence from condenser 27 via conduit 32 and 33 to fuel well 19 of the carburetor 13. The column 29 is seen to be supported at the fire wall 34 of the engine compartment by support straps 35 and 36 adjacent to condenser 27. The condenser 27 is modified, of course, to include a vapor-liquid separator so as to provide a liquid fraction which exits from the condenser 27 via conduit 32 for travel to the fuel well 19, and a vapor fraction which is recycled through the pump 31 to the condenser 27.

Note that the method of the present invention contemplates operation at rather low operating temperatures (i.e., at operating temperatures encountered in the normal operation of an automobile). Thus, the design engineer must take the anticipated temperature conditions as well as the following other design factors into consideration in designing column 29: the pressure of operation, the feed rate, the number of trays, (or character of the packing material should a packed column be used), the properties and composition of the desired overhead and bottom products, (i.e., stripping and absorption factors), the column and tray capacity, and the separation period per starting cycle. In this regard, the complexity of such operations in analogous process equipment is set forth in general in Science of Petroleum, Oxford University Press 1938) Vol. ll, Section 25, pages 15, 43 et seq, and in KirkOthmer Encyclopedia of Chemical Technology, 2nd Ed., Vol. I, Absorption page 43, et seq and Vol. 7, Distillation" page 43 et seq. With regard to the last-mentioned factor, it is apparent that the separation cycle must be short in order to provide adequate amounts of overhead product at the fuel well 19 to effect starting of the engine. In this regard, for a quite short separation cycle of say less than 1 second, the cold start system of the present invention provides sufficient amounts of overhead product containing increased lower molecular weight concentration to assure cold starting of the engine under a variety of operating conditions. These amounts can be surprisingly low, say in the range 400-600 milliliters per starting cycle.

It is apparent that if the fuel well 19 contained residual full-flow gasoline at cold start, a deluted cold start fuel charge would result. In this regard, consider the function of drain conduit 40 connected between fuel well 19 and gas tank 23 in FIG. 1. When the engine is in an inactive state, fuel within the fuel well 19 drains therefrom via the drain conduit 40 to the gas tank. As shown, conduit 40 is provided with an orifice valve 41 so as to control the rate of drainage of the fuel, say at a rate which will allow total removal of resident fuel within a 6-l 2 hour period. Thus, when the engine is inactive overnight, the drain conduit 40 in cooperation with orifice valve 41 provides for total removal of the fuel-range fuel from the fuel well 19. It should also be apparent that if the drainage conduit 40 is mounted at the side well of the fuel well 19 (not at the bottom wall as shown) not all the full-range fuel would be so drained. Instead, a residual reservoir remains, the amount of which is a function of the connector position relative to the top wall of the fuel well. For example, if the connector between the side wall of the fuel well and the conduit 40 is at a location say about two-thirds of the way from the top wall, the residual fuel therein would be one-third of the total fuel well capacity. During initial starting of the engine, the position of the discharge nozzle 20 and the connector could be arranged, depthwise, so that a selected, compatible mixture of the residual and separated fuels would enter the carburetor at cold start and allow starting of the engine.

Since successful separation of the low and high molecular weight components within stripping column 29 is based on, inter alia, the flow rate of the feed gasoline therethrough, consideration of metering valve unit b between the discharge side of fuel pump 24 and the inlet side of stripping column 29, is in order. As indicated in FIG. I, the valve unit 25b includes a vertical passageway 45 intersecting a horizontal bore 47. Passageway 45 connects exteriorly to cold start rotary valve 250 by way of conduit 46. At a remote end, the horizontal bore 47 is seen to be enlarged to form central chamber 48. Within the chamber 48 is a bimetallic diaphragm 49. The diaphragm 49 is attached, at an outer edge, to the side wall of the chamber 48, and at an inner edge to metering pin 50. The spring force provided by the diaphragm 49 is seen to be in opposite direction to the spring force provided by compression spring 51 so as the rectilinear travel of the metering pin 50 within opening 47 can be controlled as a function of temperature. In that way, the amount of full-boiling gasoline appearing at the inlet side of the stripping column 29 (i.e. at conduit 28) can be carefully controlled as a function of temperature.

FIG. 2 illustrates the metering pin 50 in more detail. As indicated, the pin 50 includes an enlarged head 51 at one end and an elongated shank portion 55 at the other end tapered to form a reduced segment 56. Reduced segment 56 is seen to be swedged as a function of length. That is to say, the reduced segment 56 is reduced in diameter starting at a beginning section 58 and ending at a mid-portion section 59. Accordingly, the amount of fuel which can be conveyed into the column 29 is dependent upon whether or not minimum section 59 or the beginning section 58 is in registry with the passageway 45, when the pin is positioned as depicted in FIG. 1.

Reference should now be had to FIGS. 1 and 3 illustrating the method aspects of the present invention. In more detail, it should be apparent that the initiation of the cold start cycle automatically occurs when the driver closes ignition switch 26c of the controller circuit 26. As a driver closes the ignition switch 26c, assume that the fuel well 19 has been emptied of fullrange fuel. Closure of ignition switch 260 activates control relay 26a of the controller circuit 26 so as to cause the cold start valve 25a to be reoriented from the position shown in FIG. 3 to the position shown in FIG. 1. Simultaneously, motor 262 is activated which in turn activates air blower 26h. Air is conveyed upwardly through the stripping column 29. As the engine turns over, the fuel pump 24 conveys full-range fuel via cold start valve 25a and inlet metering unit 25b to stripping column 29. Within the column 29, the full range fuel cascades from tray to tray countercurrent with upwardly moving air, which culminates in the production of an overhead product at conduit 30 rich in lower molecular weight components. From the exit conduit 30, the enriched overhead product is conveyed through condenser 27 then after liquefaction, via conduits 32 and 33 to the fuel well 19 and thence into carburetor 13 where the fuel charge and air are properly mixed for consumption within the combustion chambers of the engine. After a selected rise in engine temperature, as measured, say by bimetal switch 26b of the controller circuit 26 positioned at the water jacket or exhaust manifold of the engine, the control relay 26a is deactivated resulting in rotary valve 25a returning to a relaxed position as shown in FIG. 3. After the cold start valve 250 returns to a relaxed position depicted in FIG. 3, the fuel intake system of the present invention is switched over to full utilization of the full-range gasoline. That is to say, fuel conveyed from fuel pump 24 then passes via inlet rotary valve 250, conduits 38 and 33 to the fuel well 19. In this regard, one-way valve 250 is seen to prevent escape of the fuel in the direction of condenser 27.

However, as the full-range fuel is being utilized, the bimetal switch 26g of the controller circuit 26 preferably remains in an activated state, and remains so activated for a period of time determined by the time required to purge the stripping column 29 and condenser 27 of remnant fuel constituents. In that way, blower 26h remains activated to provide the purging air for this aspect of the present invention. The purged materials pass from the column 29 and condenser 27 through one-way spring valve 250 into fuel well 19. At the end of the purging cycle, the bimetal switch 263 is opened, deactivating the motor 26e and blower 26h.

While certain preferred embodiments of the inven tion have been specifically disclosed above, it should be understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art. For example, in order to improve column efficiency as well as to reduce the separation cycle time required to produce the enriched overhead product, it may be desirable to utilize the cold start system of the present invention only after the engine has warmed and the warmed air could be utilized at the inlet side of blower 26h. In that way, the warmed air could be conveyed through the column 29 in countercurrent direction to the downwardly cascading full range fuel. However, such modification would require the position of a holding tank between the condenser 27 and one-way spring valve 250. After a holding tank is filled to set point level and so indicated in the manner of US. Pat Nos. 3,498,320 and 3,5 80,263 assigned to the assignee of the present application for Pressure Liquid Level Indicator," the retained liquid could be released for cold starting through operation of cold start release .valve (not shown) under control of controller circuit 26. Thus the invention is to be given in the broadest possible interpretation within the terms of the following claims.

I claim:

1. Apparatus for reducing exhaust and inoperative pollutants produced by a spark ignition internal combustion engine of the type including an air intake system, fuel intake system, and a carburetor intercom nected therebetween for mixing said full-range fuel with air to form a combustible mixture for delivery to combustion chambers of said engine, comprising:

i. a stripping column adapted to selectively strip higher molecular weight constituents from said full-range fuel at all engine start conditions during flow through said column so as to provide a cold start fuel vapor effluent composed essentially of only low molecular weight constituents and a bottom liquid product composed essentially of only high molecular weight constituents,

ii. valve and conduit network means attached between said stripping column, a reservoir means for said full-range fuel and said carburetor, for providing selective flow conditions, said network means including a first plurality of conduit and valve means including first and second valve means controlling flow of said full-range fuel relative to said stripping column and said carburetor so as to allow, (a) in a first operating state, flow of said full-range fuel from said reservoir means to said stripping column and fiow of said cold start fuel vapor effluent to a fuel well of said carburetor to provide for rapid starting of said engine without producing excessive exhaust pollutants and, (b) in a second operating state, full-range fuel to flow directly from said reservoir means to said fuel well of said carburetor bypassing said stripping column after said engine is in a normal running condition,

iii. condenser means positioned between said second valve means and said stripping column in operative contact with said cold start vapor effluent for providing liquefaction thereof,

iv. control means operatively connected to said first valve means of said valve and conduit network for changing operating state thereof so as to direct fuel flow relative to said stripping column, said reservoir and carburetor as a function of engine operating temperature,

. said network means also including a metering means positioned between said first valve means and said stripping column for metering flow of said full-range fuel to said column as a function of temperature, said metering means including a housing having an inlet opening in fluid contact with said first valve means, movable rod means projecting into said opening and a spring-loaded bimetallicdiaphragm means permanently attached both at a central region to said rod means and at an outer edge to said housing, for controlling movement of said rod means relative to said inlet opening whereby full-range fuel flow to said stripping column is accurately controlled as a function of temperature. 

1. Apparatus for reducing exhaust and inoperative pollutants produced by a spark ignition internal combustion engine of the type including an air intake system, fuel intake system, and a carburetor interconnected therebetween for mixing said full-range fuel with air to form a combustible mixture for delivery to combustion chambers of said engine, comprising: i. a stripping column adapted to selectively strip higher molecular weight constituents from said full-range fuel at all engine start conditions during flow through said column so as to provide a cold start fuel vapor effluent composed essentially of only low molecular weight constituents and a bottom liquid product composed essentially of only high molecular weight constituents, ii. valve and conduit network means attached between said stripping column, a reservoir means for said full-range fuel and said carburetor, for providing selective flow conditions, said network means including a first plurality of conduit and valve means including first and second valve means controlling flow of said full-range fuel relative to said stripping column and said carburetor so as to allow, (a) in a first operating state, flow of said fuLl-range fuel from said reservoir means to said stripping column and flow of said cold start fuel vapor effluent to a fuel well of said carburetor to provide for rapid starting of said engine without producing excessive exhaust pollutants and, (b) in a second operating state, full-range fuel to flow directly from said reservoir means to said fuel well of said carburetor bypassing said stripping column after said engine is in a normal running condition, iii. condenser means positioned between said second valve means and said stripping column in operative contact with said cold start vapor effluent for providing liquefaction thereof, iv. control means operatively connected to said first valve means of said valve and conduit network for changing operating state thereof so as to direct fuel flow relative to said stripping column, said reservoir and carburetor as a function of engine operating temperature, v. said network means also including a metering means positioned between said first valve means and said stripping column for metering flow of said full-range fuel to said column as a function of temperature, said metering means including a housing having an inlet opening in fluid contact with said first valve means, movable rod means projecting into said opening and a spring-loaded bimetallic-diaphragm means permanently attached both at a central region to said rod means and at an outer edge to said housing, for controlling movement of said rod means relative to said inlet opening whereby fullrange fuel flow to said stripping column is accurately controlled as a function of temperature. 